1. Field of the Invention
The present invention relates to a magnetic resonance imaging system and a Radio Frequency (RF) coil. Particularly, the present invention relates to a magnetic resonance imaging system and an RF coil that can suppress heat generated around the RF coil.
2. Description of the Related Art
A magnetic resonance imaging system applies a high-frequency magnetic field over a subject placed in a static magnetic field, detects a nuclear magnetic resonance signal emitted from the subject with the high-frequency magnetic field, and reconstructs an image. Such magnetic resonance imaging system includes an RF coil that applies the high-frequency magnetic field over the subject, and detects a magnetic resonance signal emitted from the subject. The RF coil can be a single coil for both transmitting and receiving that performs application of a high-frequency magnetic field and detection of a magnetic resonance signal, or separate coils for transmitting and receiving to perform respective operations.
Generally, an RF coil is formed by using thin conductive members, such as copper foil, and the conductive members are connected to certain circuit elements for controlling operation of the RF coil. For example, a capacitor included in a resonant circuit for resonating the frequency of a high-frequency magnetic field with a resonance frequency, and/or a P-Intrinsic-N (PIN) diode configured to be a switch for switching the operation mode between transmitting and receiving when the RF coil is configured to be used for both transmitting and receiving, are connected to the RF coil.
Such circuit elements generate heat when a current is supplied. Consequently, when the magnetic resonance imaging system is operated, heat is generated around the RF coil. The heat can be conducted to the subject. For this reason, during operation of the magnetic resonance imaging system, the heat generated around the RF coil needs to be appropriately cooled. To solve the problem, a technology is contrived for cooling heat generated in a magnetic resonance imaging system by providing a cooling device in the magnetic resonance imaging system, and feeding cooling air to a portion that may generate heat, such as an area around an RF coil by using the cooling device (for example, see JP-A H8-322815 (KOKAI)).
However, heat is locally generated due to heat generation by various circuit elements around an RE coil, so that sometimes heat generation cannot be efficiently suppressed in some cases only by simply feeding cooling air to the RF coil as conventionally performed. Such phenomenon is often observed when a large current needs to be supplied to the RF coil, for example, when scanning a heavy subject.